Disk array device

ABSTRACT

A disk array device comprises: a hard disk drive module including a disk for recording information thereon and having one side that has a length substantially equal to the diameter of the disk; a battery module; an operation module; a fan module having at least one cooling fan; a controller module having a controller; a power supply module provided for supplying power to the modules; a circuit board to which the above-mentioned modules are connected via electrical connectors; and a substantially box-shaped chassis in which the modules and the circuit board are housed. A front surface and a rear surface of the chassis are opened in a rectangular shape. A length of one side of the opened front surface of the chassis is substantially the same length as the one side of the hard disk drive module.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority upon Japanese Patent ApplicationNo. 2002-174947 filed Jun. 14, 2002, which is herein incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a disk array device.

2. Description of the Related Art

A disk array device for use as an external storage device in a computersystem generally comprises hard disk drives, a controller, a powersupply, a battery, an enclosure, and a fan. These components are placedwithin a single housing. In the event of a power failure, the batterysupplies power so that cached data is written on a hard disk drive toautomatically initiate and complete a planned shutdown for the purposeof avoiding the loss of cached customer data. When a disk array unit isadded, the enclosure controls relaying and/or connection in relation tothe added unit. In order to prevent the housing internal temperaturefrom rising, the fan takes in air from the outside of the housing toforcibly replace internal air with external air.

It is highly requested that such a disk array device be downsized.However, the size of the disk array device generally increases with anincrease in its storage capacity. This is because, since the use of alarger number of hard disk drives and a higher-performance controller isrequired to provide a large storage capacity, a large-size power supplyand a cooling device have to be provided. To provide adequate coolingperformance, it is also necessary to consider the device's internalventilation. When a plurality of disk array devices of a greater size isadded for use, the required installation area increases accordingly.

Under these circumstances, various techniques have been proposed with aview toward decreasing the size without sacrificing the coolingperformance. For example, the technique disclosed by Japanese PatentApplication Laid-open Publication No. JP-2001-338486-A separates acooling air flow path into two. One path is used for the flow of coolingair provided by a fan that is attached to a power supply module, whichis mounted in the upper part of a disk array device. The other path isused for the flow of cooling air provided by a cooling fan module, whichis mounted on a lateral surface of the lower part of the disk arraydevice. Further, a heating element and a power supply module with acooling fan are positioned after the air flow paths. This decreases thefront-to-rear dimension of the disk array device without sacrificing thecooling performance.

However, the technique disclosed by Japanese Patent Application Laid-penPublication No. JP-2001-338486-A cannot reduce the height of the diskarray device when the cooling air flow path is separated into the pathfor the cooling air provided by the power supply module in the upperpart of the device and the path for the cooling air provided by thecooling fan module in the lower part of the device. Further, if the fanmodule in the lower part of the device becomes faulty, the device'slower part cooling efficiency decreases. Furthermore, a cooling fan isprovided in both the upper and lower parts of the device. As a result, alarge number of cooling fans are used for the whole disk array device.

SUMMARY OF THE INVENTION

The present invention provides a disk array device comprising: a circuitboard having electrical connectors; a hard disk drive module connectedto the circuit board via at least one of the electrical connectors,including a disk for recording information thereon, and having one sidethat has a length substantially equal to the diameter of the disk; abattery module connected to the circuit board via at least one of theelectrical connectors; an operation module connected to the circuitboard via at least one of the electrical connectors; a fan moduleconnected to the circuit board via at least one of the electricalconnectors and having at least one cooling fan; a controller moduleconnected to the circuit board via at least one of the electricalconnectors and having a controller; a power supply module connected tothe circuit board via at least one of the electrical connectors andprovided for supplying power to the modules; and a substantiallybox-shaped chassis in which said modules and said circuit board arehoused, a front surface and a rear surface of which being opened in arectangular shape; wherein a length of one side of the opened frontsurface of the chassis is substantially the same length as the one sideof the hard disk drive module.

Objects of the present invention and solutions provided by the presentinvention will be apparent from the following description of theembodiments of the invention and the accompanying drawings.

According to the present invention, it is possible to provide a diskarray device that has substantially the same height as a hard disk drivemodule. Further, it is also possible to cool the interior of the chassiswith high efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described inconjunction with the accompanying drawings, in which:

FIG. 1 is an external perspective view of a disk array device accordingto one embodiment taken from the front right-hand side;

FIG. 2 is a projection of a hard disk drive module according to theembodiment;

FIG. 3 is an external perspective view of an operation module accordingto the embodiment taken from the front right-hand side;

FIG. 4 is an external perspective view of a disk array device accordingto the embodiment taken from the rear left-hand side;

FIG. 5 is a schematic cross-sectional view taken along line V-V of adisk array device according to the embodiment;

FIG. 6 is a schematic cross-sectional view taken along line VI-VI of adisk array device according to the embodiment;

FIG. 7 is a schematic cross-sectional view taken along line VII-VII of adisk array device according to the embodiment;

FIG. 8 is an external perspective view of a circuit board according tothe embodiment taken from the rear right-hand side;

FIG. 9 illustrates how a circuit board provided with high-precisionpositioning means according to the embodiment is mounted on a chassis;

FIG. 10 is a schematic cross-sectional view taken along line X-X of adisk array device according to the embodiment;

FIG. 11 illustrates how cooling air flows within a disk array deviceaccording to the embodiment;

FIG. 12 illustrates how cooling air provided by a single fan flowswithin a disk array device according to the embodiment; and

FIG. 13 is a projection of a power supply module according to oneembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described in detailwith reference to the accompanying drawings.

A disk array device according to one embodiment of one aspect of thepresent invention comprises: a circuit board having electricalconnectors; a hard disk drive module connected to the circuit board viaat least one of the electrical connectors, including a disk forrecording information thereon, and having one side that has a lengthsubstantially equal to the diameter of the disk; a battery moduleconnected to the circuit board via at least one of the electricalconnectors; an operation module connected to the circuit board via atleast one of the electrical connectors; a fan module connected to thecircuit board via at least one of the electrical connectors and havingat least one cooling fan; a controller module connected to the circuithoard via at least one of the electrical connectors and having acontroller; a power supply module connected to the circuit board via atleast one of the electrical connectors and provided for supplying powerto the modules; and a substantially box-shaped chassis in which saidmodules and said circuit board are housed, a front surface and a rearsurface of which being opened in a rectangular shape. A length of oneside of the opened front surface of the chassis is substantially thesame length as the one side of the hard disk drive module.

According to such a configuration, it is possible to reduce the diskarray device size. Since the installation area occupied by the diskarray device can be decreased by downsizing of the disk array device, itbecomes possible to reduce the computer system running cost.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the circuit board is capable of beingattached in the chassis parallel to the opened front surface; the harddisk drive module is connected to a front side of the circuit board fromthe opened front surface of the chassis, the one side of the hard diskdrive module being aligned with the one side of the opened front surfaceof the chassis; the battery module is connected to the front side of thecircuit board from the opened front surface of the chassis in a positionadjacent the hard disk drive module; and the controller module, thepower supply module, and the fan module are connected to a rear side ofthe circuit board from the opened rear surface of the chassis.

According to such a configuration, the hard disk drive module and thebattery module can be inserted/removed into/from the front of the diskarray device for module insertion/removal purposes. Therefore,maintenance and inspection of the disk array device can be made withease. Further, by arranging the power supply module, the controllermodule, and the fan module at the rear of the disk array device, itbecomes possible to prevent changes to the device, such as cablingchanges and setting changes, from being made easily. These featuresincrease the disk array device's serviceability, maintainability, andsecurity.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the circuit board has a front circuitboard to which at least the hard disk drive module and the batterymodule are connected to the front side thereof, and to which the powersupply module and the fan module are connected to the rear side thereof,and a rear circuit board to which the controller module is connected;and the front circuit board and the rear circuit board are positionedadjacent and parallel to each other and connected together with anelectrical connector.

According to such a configuration, the circuit board size can bereduced. As a result, the circuit board can be mounted within a chassisfor a small-size disk array device.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the controller module has a managementportion for managing additional installation of a disk array device.

Conventionally, additional disk array device installation was managed byan independent module called an “enclosure”. However, according to theconfiguration mentioned above, it is possible to decrease the number ofmodules and reduce the disk array device size. The management portionfor managing additional installation of a disk array device is used toprovide integrated access control for each of the hard disk drivemodules mounted in a plurality of disk array devices, in case a diskarray device is additionally installed. As described later, themanagement portion for managing additional installation may be realizedby, for example, a memory or the like in the controller module thatstores an appropriate program, and a CPU in the controller module thatcan execute the program.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the controller module is substantiallyflat; a plurality of the controller modules are capable of being bearranged on the circuit board adjacent to each other in a direction ofthe height of the chassis to maximize the area in which the controllermodules oppose each other; and the connectors for connecting each of thecontroller modules to the circuit board are arranged on the circuitboard in the diction of the height of the chassis.

According to such a configuration, the length of the wiring on thecircuit board for connecting the controller modules can be minimized.This decreases the wiring space, thereby reducing the size of thecircuit board. Further, since crosstalk between wires can be avoided, itbecomes possible for the controller modules to share a cache, therebyenhancing the disk access performance.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the chassis has at least one holeand/or at least one protrusion; and the circuit board has at least oneprotrusion that fits into the hole of the chassis and/or at least onehole into which the protrusion of the chassis fits.

According to such a configuration, the circuit board can be directlyattached to the chassis with high accuracy. This also makes it possibleto reduce the number of parts for mounting the circuit board on thechassis, thereby reducing the size of the chassis.

In another aspect of the disk array device according to the presentembodiment, it is possible that: at least two of the fan modules areprovided; and at least one of the fan modules is arranged near each sidesurface of the chassis.

According to such a configuration, the interior of the chassis can becooled without having to furnish the power supply module with a fan.This results in downsizing of the disk array device.

Further, it is possible that: cooling air flow provided by the fanmodules is introduced from the front of the chassis to cool at least thehard disk drive module and the battery module, cools, in the rear of thecircuit board, the power supply module and the controller module, istaken in by the fan modules provided near both of the side surfaces ofthe chassis, and is discharged out of the rear of the chassis.

According to such a configuration, heated air in the chassis isdischarged from the fan module on each side of the chassis. Therefore,the interior of the chassis can be efficiently cooled.

Further, it is possible that: each of the fan modules has a plurality ofcooling fans; and air outlets of each of the cooling fans are orientedin directions different from each other to avoid interference betweencooling air flow.

According to such a configuration, the cooling fans can discharge airwith high efficiency. As a result, warmed air within the chassis can beefficiently discharged.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the fan module is arranged near atleast one side surface of the chassis; a partitioning plate is providedsubstantially in the middle of both side surfaces of the chassis; a setof the power supply modules is provided, and at least one of the powersupply modules is arranged on each side of the partitioning plate; thecontroller module is arranged across the partitioning plate; and thepartitioning plate is provided with a vent hole.

When the partitioning plate having such a configuration is used, itbecomes possible to circulate cooling air within the chassis with onlyone fan module. Therefore, even if one of the fan modules becomesfaulty, the whole chassis can be continuously cooled. As a result, theavailability of the disk array device can be enhanced.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the controller module is substantiallyflat; and the circuit board has a plurality of holes extending in adirection parallel to the controller module.

According to such a configuration, the cooling air flow within thechassis is rectified when it passes through the circuit board. As aresult, the cooling air flow within the chassis is properly adjusted toefficiently cool the interior of the chassis.

In another aspect of the disk array device according to the presentembodiment, it is possible that the length of the one side of the openedfront surface of the chassis is between 128 mm and 129 mm when thediameter of the disk is 3.5 inches.

According to such a configuration, the height of the disk array devicecan be set to no more than 3U (approximately 133.35 mm), which isdefined by the EIA Standard EIA-310-D.

In another aspect of the disk array device according to the presentembodiment, it is possible that: the operation module includes an alarmbuzzer stop switch, and a power switch for the disk array device, thepower switch having an ON-side for turning the disk array device ON andan OFF-side for turning the disk array device OFF; and the alarm buzzerstop switch is arranged on the side of the ON-side of the power switch.

According to such a configuration, it becomes possible to prevent thedisk array device from being turned OFF even if the power switch isinadvertently touched when the alarm buzzer stop switch is pressed tostop an alarm buzzer that sounds in the event of an error.

Further, it is possible that: a setting switch is provided inside theoperation module; and the setting switch is capable of being manipulatedfor setup from a space in front of a hard disk drive module adjacent theoperation module.

This minimizes the volume occupied by the operation module for diskarray device setup.

FIG. 1 is an external perspective view of the disk array device takenfrom the front right-hand side.

A front decorative door 300 is mounted on a chassis 100 in such a mannerthat the front decorative door 300 is removable. Further, louvers 301are mounted on the front decorative door 300 in such a manner that threelouvers 301 form a unit and the louvers 301 are removable on aunit-by-unit basis. The louvers 300 are available in various colorsaccording to design and can be replaced as needed. The front decorativedoor 300 also provides adequate ventilation. As described later, modulesof fans 800 (hereinafter referred to as the fan modules) take in outsideair into the chassis 100 via the front decorative door 300 in order tocool the interior of the chassis 100 and discharges air out from therear of the chassis 100. Vent holes 112 are used to discharge air out ofthe chassis 100 and provided on both sides of the chassis 100.

There is an opening at the front of the chassis 100. A lug 101 isprovided on the right- and left-hand sides of the opening. From theleft-hand side, hard disk drive modules 200 (referred to herein as HDDmodules 200 in the present embodiment) are sequentially positioned inthe front opening of the chassis 100 in such a manner that the HDDmodules 200 are removable. Each HDD module 200 can be removed with itshandle 201. FIG. 2 is a projection of a HDD module. A plurality of ventholes 203 are provided in the front surface of a HDD module. Anelectrical connector 202 is mounted on the rear of a HDD module. EachHDD module 200 has inside a 3.5-inch (approximately 88.9 mm) disk as arecording medium and has a height of approximately 115.8 mm. Each HDDmodule is positioned within the chassis 100 in such a manner that thedirection of the disk diameter is in the height direction of the HDDmodule. The front opening in the chassis 100 is large enough to housefourteen HDD modules 200 from the left-hand side.

Further, as shown in FIG. 1, the rightmost part of the front opening inthe chassis 100 is used to house a module 500 of a battery (hereinafterreferred to as the battery module 500) and a module 400 of an operationpanel (hereinafter referred to as the operation module 400). The batterymodule 500 supplies power as needed to write cached data onto a harddisk drive and to automatically initiate and complete a planned shutdownin the event of a power failure for avoiding the loss of cached customerdata. Since the power stored in the battery module 500 graduallydecreases with time, the battery module 500 needs to be exchangedperiodically. For this reason, the battery module 500 is mounted at thefront of the chassis 100 so as to facilitate its replacement.

The disk array device can be mounted in a 19-inch rack-type housingcompliant with the EIA Standard EIA-310-D. When considering both theheight of the HDD modules 200 having a 3.5-inch diameter disk (theheight of the HDD module is approximately 115.8 mm) and the 3U heightlimit for the disk array device defined by the EIA Standard EIA-310-D,the height of the disk array device should be between 115.8 mm and 133.3mm. Further, when the positional relationship between the HDD modules200 and disk array device is considered to keep the HDD modules out ofcontact with the disk array device, it is preferable that theapproximate height of the disk array device be between 128 mm and 129mm.

The operation module 400 will now be described with reference to FIG. 3.In order to realize disk array device downsizing, the operation module400 is designed so as to minimize the volume that it occupies. The frontof the operation module 400 carries only a power switch 401 and an alarmbuzzer stop switch 404. A setting switch 405 is mounted inside themodule together with an alarm buzzer 406. The power switch 401 functionsas a power switch for the disk array device. When an error occurs in thedisk array device, the alarm buzzer 406 sounds to alert the maintenancepersonnel to the encountered error. The alarm buzzer stop switch 404 isused to shut off the alarm buzzer 406. Pressing the alarm buzzer stopswitch 404 silences the alarm buzzer. The setting switch 405 is used toset up the disk array device. For example, the setting switch 405 isused to toggle between remote control and local control modes. If, forinstance, an external UPS (Uninterruptible Power Supply) is installed,the setting switch 405 is used to change the interlock control mode forthe UPS.

Since the volume occupied by the operation module 400 is minimized, thepower switch 401 and alarm buzzer stop switch 404 mounted on the frontof the operation module 400 are positioned close to each other.Therefore, when the alarm buzzer stop switch 404 is pressed to silencethe alarm buzzer in an emergency such as when an error alarm is given,there is a possibility that the power switch 401 may be inadvertentlytouched. As such being the case, the power switch 401 is arranged sothat, when the side 402 of the power switch 401 closer to the alarmbuzzer stop switch 404 is pressed, the disk array device is turned ONand that,

when the side 403 of the power switch 401 far from the alarm buzzer stopswitch 404 is pressed, the disk array device is turned OFF. Such aconfiguration prevents the disk array device from being shut downunexpectedly due to an operating error. It should be noted that, even ifthe alarm buzzer stop switch 404 is inadvertently pressed when pressingthe power-ON side 402 of the power switch 401, no particular problemarises.

The setting switch 405 is provided inside the operation module 400. Thereason to this is that remote/local control mode switching and otherdisk array device setup operations are less frequently performed thanthe use of the power switch 401 and alarm buzzer stop switch 404.However, low user-friendliness results if, for instance, the disk arraychassis has to be disassembled for the purpose of adjusting the internalsetting switch 405. Therefore, an opening 407 is provided in a lateralpart of the operation module 400 so that the setting switch 405 caneasily be adjusted without having to disassemble the disk array devicechassis. The setting switch 405 can be accessed for adjustment purposesby inserting a tool into the opening 407 in the direction of the arrow408 while making use of a space 204 that is provided near the HDD moduledetachment handle 201 of a HDD module 200 next to the operation module400. As a result, operational ease can be provided while minimizing thevolume occupied by the operation module.

It should be understood that the configurations described above arepresented by way of example only. For instance, the height of the diskarray device is not limited to 3U. Further, a total of fifteen HDDmodules 200 can be mounted by installing one additional HDD module 200in the chassis's front rightmost position in which the battery module500 and operation module 400 are mounted. This alternative configurationcan be achieved because the combination of the battery module 500 andoperation module 400 is configured to be equal to the HDD modules 200 inwidth and height. If this alternative configuration is used, the batterymodule 500 and operation module 400 will be installed in anotherposition of the chassis 100. For an additionally installed disk arraydevice, which does not require its own battery module 500 and operationmodule 400, fifteen HDD modules 200 are arrayed at the front of thechassis. By configuring the combination of the battery module 500 andoperation module 400 to be equal to the HDD modules 200 in width andheight as described above, the same basic structure can be applied toboth an initial disk array device chassis and additional disk arraydevice chassis. This results in reducing the design cost andmanufacturing cost.

FIG. 4 is an external perspective view of a disk array device accordingto the present embodiment taken from the rear left-hand side.

The rear surface of the chassis 100 is open. Fan modules 800 are mountedon both the right- and left-hand sides of the chassis 100 in such amanner that the fan modules 800 are removable. Two modules 600 of powersupply (hereinafter referred to as the power supply modules 600) areprovided between the right- and left-hand fan modules 800. Two modules700, 702 of controllers (hereinafter referred to as the controllermodules 700, 702) are vertically arranged below the power supply modules600. The power supply modules 600 and controller modules 700 and 702 canall be removed separately. It should be noted that the disk array deviceis operable even when it is provided with only one unit each of the fanmodule 800, power supply module 600, and controller module 700 (702)instead of two units each.

The fan modules 800 are provided to cool the interior of the chassis100. Although the fan modules 800 are described in detail later, theyhave three internal fans 802, 803, 804, which take in warmed air withinthe chassis 100 and discharge it outside to cool the interior of thechassis 100. Air is discharged through air outlet slits 801 provided inthe rear of each of the right- and left-hand fan modules 800 and throughvent holes 112 provided in both sides of the chassis 100.

The power supply modules 600 supply electrical power to the entire diskarray device. An AC input connector section 606 is mounted on the rearof each power supply module 600 to input AC power. The input AC power isconverted to DC power by an AC/DC converter circuit on a power supplycircuit board in each module and then supplied to the entire disk arraydevice. A detachment handle 601 is mounted on the rear of each powersupply module 600 for module insertion/removal. The power supply modules600 are not provided with a fan. Although a fan is mounted on the rearof a conventional disk array device to cool the power supply module, thedisk array device according to the present embodiment cools the powersupply modules 600 using only the fan modules 800, which are mounted onboth sides of the chassis 100. To enhance the efficiency of coolingprovided by the fan modules 800, the rear surface of each power supplymodule 600 is covered to admit no outside air.

As a result, warmed air inside the power supply modules 600 isefficiently taken in by the fan modules 800. Further, warmed airexpelled by the fan modules 800 is blocked from returning to theinterior of the chassis 100, thereby preventing circulation of warmedair. Furthermore, the front-to-rear dimension of each power supplymodule 600 is reduced because no fan is mounted on the rear of themodule 600.

Controller modules 700 and 702 provide control of the disk array device,and incorporate a control circuit board, which carries a CPU (CentralProcessing Unit), memory, cache, and other components. Controllermodules 700 and 702 are configured so as to share their caches. Thisresults in an increase in the available cache capacity, therebyincreasing the speed of data access from a host computer.

In order to share caches, however, the speed of data transfer betweenthe controller modules 700 and 702 needs to be in the order of a CPUclock speed. To achieve such a high data transfer speed, it is necessaryto minimize the influence of wiring capacitance and inductance as wellas the influence of mutual interference (crosstalk) between adjacentwires. To accomplish this, it is necessary to minimize the wiringlength. Although details will be given later, the disk array deviceaccording to the present embodiment minimizes the wiring length bypositioning the two controller modules 700, 702 adjacent to each otherin the direction of the height of the chassis 100 to maximizing theopposing areas of the controller modules.

In conventional devices, an enclosure is provided independently of acontroller module; however, in the disk array device according to thepresent embodiment, an enclosure is incorporated as an integralcomponent. The enclosure is a device that has means for managingadditional installation of a disk array device. More specifically, theenclosure has a management function that provides integrated accesscontrol for each of the HDD modules 200 mounted in a plurality of diskarray devices, in case a disk array device is additionally installed. Itis possible to reduce the disk array device size by furnishing thecontroller modules 700 and 702 with an enclosure function and decreasingthe number of modules.

The rear of controller modules 700 and 702 is provided with an interfacefor communicating with an external device. As is the case with the powersupply modules 600, the rear of controller modules 700 and 702 is notprovided with vent holes. Therefore, the cooling air provided by the fanmodules 800 smoothly flows within controller modules 700 and 702 and isthen discharged. No warmed air flows inward from the outside.

The internal parts arrangement of the disk array device will now bedescribed with reference to FIGS. 5 to 10.

FIG. 5 is a schematic cross-sectional top view, which illustratescross-section taken along line V-V of the disk array device shown inFIG. 4. The HDD modules 200 and battery module 500 are mounted in thefront opening in the chassis 100. The fan modules 800 and power supplymodules 600 are mounted in the rear opening of the chassis 100. Themodules in the front opening and the modules in the rear opening are allconnected to a circuit board 900.

The HDD modules 200 are slidably mounted in the front of the chassis 100so that they can be exchanged easily. Each HDD module 200 is equippedwith a detachment handle 201 so that the module 200 can easily beremoved from and reinserted into the chassis 100. The rear of each HDDmodule 200 is equipped with a connector 202, which is connected to a HDDmodule connector 902 provided on the circuit board 900. By connectingthese connectors 202 and 902, data is read/write from/to a HDD module200. In order to ensure the strength of the chassis 100, the compartmentfor the HDD modules 200 is provided with two partitioning plates 102,103.

As is the case with the HDD modules 200, the battery module 500 isslidably mounted in the front of the chassis so that it can be exchangedeasily. The battery module 500 is not equipped with a detachment handlebecause it is less frequently removed and reinserted than the HDDmodules 200; however, it is needles to say that the battery module 500can be equipped with such a detachment handle. The battery module 500 isequipped with a connector 501, which is connected to a battery moduleconnector 904 provided on the circuit board 900. By connecting theseconnectors 501 and 904, the electrical power stored in the batterymodule 500 can be supplied to the disk array device in the event of apower failure.

The power supply modules 600 are mounted in such a manner that they canbe removed and reinserted from the rear of the chassis 100. Two powersupply modules 600 can be mounted adjacent to each other. Since thepower supply modules 600 are relatively heavy, each of them is equippedwith a handle 601 for ease of removal/insertion. Each power supplymodule 600 is equipped with a connector 602, which is connected to apower supply module connector 903 provided on the circuit board 900. Byconnecting these connectors 602 and 903, electrical power is supplied tothe modules in the disk array device.

The fan modules 800 are mounted on both sides of the chassis 100 in sucha manner that they can be removed and reinserted. Each fan module 800 isequipped with a connector 805, which is connected to a fan moduleconnector 901 on the circuit board 900. By connecting these connectors805 and 901, a fan control signal and electrical power are received.Each fan module 800 incorporates three fans 802, 803, 804. These fanstake in air from intake surfaces 809, 807, and 808, which face the powersupply module, and discharge air from air outlets 806, 807, and 808,which face the rear of the chassis 100. If the flows of air dischargedby the fans 802, 803, 804 interfere with each other, the air-dischargeefficiency lowers due to air flow disturbance. To avoid such a problem,the fans 802, 803, 804 are arranged in such a manner so that the airoutlets 806, 807, 808 face towards different directions.

Partitioning plates 104, 106 are positioned between the fan modules 800and power supply moues 600. Another partitioning plate 105 is alsopositioned between the two power supply modules 600. As described later,these partitioning plates have vent holes so that the cooling airprovided by the fan modules 800 efficiently flows within the chassis100.

FIG. 6 is a schematic cross-sectional top view, which illustratescross-section taken along line VI-VI of the disk array device shown inFIG. 4. The HDD modules 200 and battery module 500 are mounted in thefront opening in the chassis 100. The fan modules 800 and controllermodule 700 are mounted in the rear opening of the chassis 100.

Behind the aforementioned circuit board 900, another circuit board 905is provided for connecting to the controller module 700. The circuitboard 900 in the front of the chassis and the circuit board 905connected to controller module 700 are hereinafter referred to as thefront circuit board 900 and rear circuit board 905, respectively. Therear circuit board 905 is equipped with connectors 906, each of whichbeing connected to connectors 701 provided on the controller module 700.The front circuit board 900 and rear circuit board 905 areinterconnected via connectors 908 and 909. Although details are givenlater, the height of the chassis is reduced thanks to the use of the twocircuit boards. The clearance between the front circuit board 900 andrear circuit board 905 is set to an optimum value. An excessiveclearance would increase the front-to-rear dimension of the chassis 100;if, on the contrary, the clearance is too small, the pins of the HDDmodule connectors 902, which penetrate through the front circuit board900, may come into contact with the pins of the controller moduleconnectors 906, which penetrate through the rear circuit board 905.Therefore, the clearance between the front circuit board 900 and rearcircuit board 905 set to an optimum value, while keeping the sizes ofconnectors 908 and 909 in mind.

The controller module 700 is mounted in such a manner that it can beremoved from and reinserted into the rear of the chassis 100. Thecontroller module 700 incorporates a control circuit board, whichcarries a CPU, memory, cache, and other components, and has an enclosurefunction (that is, has a management portion for managing additionalinstallation) for managing additional disk array device installations.The management portion for managing additional installation may berealized by, for example, a memory or the like in the controller module700 that stores an appropriate program, and a CPU in the controllermodule 700 that can execute the program. The controller module 700 isconnected to the various modules in the disk array device via the rearcircuit board 905, and controls and manages the various modules.

Partitioning plates 104, 106 with vent holes are provided between thecontroller module 700 and the fan modules 800. These partitioning platesare the same as the partitioning plates provided between the powersupply modules 600 and the fan modules 800.

FIG. 7 is a schematic cross-sectional right-side view, which illustratescross-section taken along line VII-VII of the disk array device shown inFIG. 4. The HDD modules 200 are mounted in the front opening in thechassis and connected to the front circuit board 900. The rear openingin the chassis houses the power supply modules 600, which are mounted inthe upper section, and the controller modules 700 and 702, which aremounted in the lower section. The power supply modules 600 are connectedto the front circuit board 900. The controller modules 700 and 702 areconnected to the rear circuit board 905.

A partitioning plate 107 is provided between the power supply nodules600 and the controller module 700. The partitioning plate 107 is joinedwith partitioning plates 104, 105, and 106 to support the power supplymodules 600 from below. A partitioning plate 108 is provided between thecontroller modules 700 and 702. The partitioning plate 108 is joinedwith partitioning plates 104 and 106 to support the controller module700 from below. No vent holes are provided in the partitioning plates107 and 108. This prevents the cooling air flow within the chassis forma fluctuating in the vertical direction and restricts disturbance of thecooling air.

The front circuit board 900 is provided with a rectification plate 910,which is installed above the rear circuit board 905. The rectificationplate 910 not only reinforces the front circuit board 900 but alsorectifies the cooling air flow within the chassis 100. The circuit boardstructure will now be described with reference to FIG. 8.

The front circuit board 900 and the rear circuit board 905 areinterconnected with connectors 908 and 909. Information exchange betweenthe front circuit board 900 and the rear circuit board 905 takes placevia the connectors 908 and 909. The connectors 908 and 909 arepositioned between the front circuit board 900 and rear circuit board905. From the illustrated viewing angle, the pins of connector 909penetrating through the rear circuit board 905 are visible.

The front and rear circuit boards 900 and 905 are secured to a circuitboard retention frame to construct a circuit board assembly 912. Therear circuit board 905 has connectors 906 and 907, which connect to thetwo controller modules 700, 702. The connectors 906 are for connectingto the controller module 700, whereas the connectors 907 are forconnecting to the controller module 702. As described above, since thecontroller modules 700 and 702 share their cache data, they need totransfer the data at a high speed between them. According to theconfiguration of the controller modules of the present embodiment, theconnectors 906 and 907 are provided on the rear circuit board 905 insuch a manner that the corresponding pins of the connectors 906 and 907,which are located next to each other in the vertical direction, arearranged in the same position in each connector. Therefore, the lengthof the wiring on the rear circuit board 905 for pin connection can beminimized. This feature provides high-speed data transfer between thecontroller modules 700 and 702, thereby letting them share their cacheddata.

Further, by dividing the circuit board into the front circuit board 900and rear circuit board 905 and providing the connectors 906 and 907 onthe rear circuit board 905, it is possible to reduce the height of thecircuit board assembly 912. The reason is that, if an attempt is made tomount connectors 906 and 907 on the rear of the front circuit board 900,they need to be mounted on the upper or lower part of the circuit boardin order to avoid interference with the pins of the HDD moduleconnectors 902 mounted on the front side.

Connectors 903 for connecting to the two power supply modules 600 andconnectors 901 for connecting to the two fan modules 800 are mounted onthe front circuit board 900. These connectors are positioned so thatthey do not interfere with the pins of the HDD module connectors 902.The same fan modules 800 are used for the module 800 mounted on theright-hand side of the chassis and for the module 800 mounted on theleft-hand side. Therefore, the right- and left-hand side connectors 901,which are both mounted on the front circuit board 900 to connect to thefan modules 800, are placed at opposite positions in the verticaldirection.

The front circuit board 900 also carries a rectification plate 910,which rectifies the cooling air flow within the chassis 100. Therectification plate 910 has a plurality of slits 911, the longitudinaldirection of which being arranged in a direction parallel to controllermodules 700 and 702. Since the air flow that passes by the HDD modules200, which are mounted at the front of the chassis 100, comes throughgaps between adjacent ones of the HDD modules 200, the flow is like avertically-spread wind. This air flow passes through holes 913 in thefront circuit board 900 and flows toward the rear of the chassis 100.The size of the holes 913 in the circuit board 900 is made as large aspossible. However, due to the limitations imposed by the wiring patternsprovided on the circuit board, the holes 913 are not shaped to optimallyrestrict disturbance in the vertically spread air flow coming out ofgaps between the HDD modules 200. Therefore, the air flow becomesdisturbed when it passes through holes 913 in the circuit board.Further, the power supply modules 600 and the controller modules 700 and702, which are mounted in the rear of the chassis 100, have internalelectronic circuit boards. These electronic circuit boards are arrangedso that their surfaces are oriented in a lateral direction within thechassis 100. In order to make the air flow smoothly in the rear part ofthe chassis 100, it is necessary to rectify the air flow so that itspreads in the lateral direction. The rectification plate 910 is mountedon the front circuit board 900 for such air flow smoothing. Therectification plate 910 has a plurality of slits 911, the longitudinaldirection of which being arranged in a direction parallel to controllermodules 700 and 702. The air flow is rectified and spreads in thelateral direction after passing through the slits 911 in therectification plate 910. As a result, the disturbance in the air flowthat flows by the controller modules 700 and 702 and the power supplymodules 600 is restricted to efficiently cool the interior of thechassis 100.

Further, the use of the rectification plate 910 increases the strengthof the circuit board 900. Inserting the connector 202 of a HDD module200 applies great force to the front circuit board 900. Therefore, ifthe front circuit board 900 is not strong enough, it may graduallydeform when the connector is inserted many times over the years. Sincethe rectification plate 910 is added to increase the circuit boardstrength, the number of other reinforcement members can be reduced. As aresult, it became possible to reduce the circuit board size.

The way of mounting the circuit board into the chassis will now bedescribed with reference to FIG. 9, which is an external perspectiveview taken from the rear left-hand side of the circuit board.

It is important to position the circuit board in the chassis at highprecision. If the positioning accuracy for such mounting is inadequate,the HDD modules 200 cannot be connected because the connectors 202 ofthe HDD modules 200 will be misaligned with the connectors 902 on theconnector circuit board. For an array of up to fourteen HDD modules 200and the battery module 500, all their connectors need to be in precisealignment.

As described above, the HDD module connectors need to be preciselyaligned with the mating connectors on the circuit board. That is why thecircuit board could not be mounted directly in the chassisconventionally. In conventional devices, a dedicated front chassis wasemployed to house HDD modules. After arrangement of the connectors inthe front chassis with high accuracy, the front chassis was fastened toa chassis main body. Due to the use of a dual chassis structure, inwhich the chassis main body incorporates another chassis (front chassis)for housing HDD modules, the disk array device could not be downsized.

The disk array device according to the present embodiment employs thefollowing configuration for mounting the circuit board in the chassismain body with high accuracy. Nuts (protrusions) 914 are fastened to thefour corners of the front of the circuit board for use in mounting thecircuit board in the chassis 100. Backboard retention plates 109 arefastened to the upper and lower sides of the chassis 100 in order toassemble the circuit board assembly 912. The circuit board retentionplates 109 have holes 110 that have substantially the same diameter asthe nuts 914 and that are positioned corresponding to the nuts 914,which are fastened to the four corners of the front of the circuitboard. When the circuit board assembly 912 is to be mounted into thechassis 100, the nuts 914, which are fastened to the four corners of thefront of the circuit board, are fitted into the circuit board mountingholes 110 and then bolted down from the front of the chassis 100.Consequently, the circuit board assembly 912 can be easily mounted inthe chassis 100 with high accuracy and without having to provide adedicated front chassis for housing the HDD modules. As a result, itbecame possible to realize downsizing of the disk array device.

In addition, the front circuit board 900 is provided with a plurality ofholes 913 for venting cooling air. The vent holes 913 in the circuitboard 900 are made to be as large as possible.

FIG. 10 is a schematic cross-sectional right-side view, whichillustrates cross-section taken along line X-X of the disk array deviceshown in FIG. 4. The battery module 500 and the operation module 400 aremounted in the front opening in the chassis 100 and connected to thefront circuit board 900. The fan modules 800 are mounted in the rearopening in the chassis 100 and connected to the front circuit board 900.The front circuit board 900 is provided with the rectification plate910.

Each fan module 800 contains three fans 802, 803, 804. The air outlets806, 807, 808 of the fans are oriented toward the chassis in such amanner that their discharged air flows do not interfere with each other.

The cooling air flow within the chassis 100 will now be described withreference to FIG. 11.

When the fans 802, 803, 804 in the fan modules 800 operate, the outsideair is taken in from the front of the chassis and is caused to flow inthe section of the HDD modules 200. The cooling air flow 1000 in thesection of the HDD modules 200 flows through the gaps between adjacentones of the HDD modules 200. Therefore, the cooling air spreads in avertical direction and flows toward the rear of the chassis. Thiscooling air flow 1000 is rectified by the rectification plate 910provided on the circuit board. The rectified cooling air flow 1001,which now spreads in a horizontal direction, is taken into the powersupply modules 600 and the controller modules 700 and 702. FIG. 13 is aprojection of a power supply module 600. As shown in FIG. 13, elongatedholes 603 that extend in the lateral direction are provided in the frontof the case of the power supply modules 600. These holes 603 are made sothat their positions and shapes agree with those of the holes in therectification plate 910. Therefore, the air flow 1001, which isrectified by the rectification plate 910, smoothly enters the powersupply modules 600. As in FIG. 11, the air flow 1002, which isintroduced into the power supply modules 600 and controller modules 700and 702, passes through the partitioning plates 104, 106, and is takeninto the right- and left-hand fan modules 800. The air flow 1003, whichis introduced into the fan modules 800, is discharged out of the airoutlets 801 in the rear of the fan modules 800 and out of the vent holes112 in both sides of the chassis 100 (1004). The positions and shapes ofthe laterally elongated holes in the partitioning plates 104, 106 agreewith those of the holes 604, 605 in both sides of the power supplymodules 600. Therefore, the cooling air flow can smoothly flow past thepartitioning plates 104, 106. Further, no vent holes are provided in therear of the power supply modules 600 or controller modules 700 and 702.This prevents the air flow 1004, which has been discharge from the fanmodules 800, from going back into the chassis 100.

The process of cooling the whole interior of the chassis 100 when onefan module 800 is faulty will now be described with reference to FIG.12. The following description applies not only to a case where one fanmodule 800 is faulty, but also to a case where only one fan module 800is installed. An example is given where only the left-hand fan module isused to cool the interior of the chassis 100.

The air flow cooing from the section of the HDD modules 200 passesthrough the rectification plate 910 and moves towards the power supplymodules 600 and the controller modules 700 and 702. The air flow 1002introduced into the left-hand power supply module 600 is taken into theleft-hand fan module 800. Further, the air flow 1005 introduced into theright-hand power supply module 600 is also taken into the left-hand fanmodule 800. The reason is that the partitioning plate 105 providedbetween the right- and left-hand power supply modules 600 is providedwith laterally elongated holes, whose positions and shapes are identicalwith those of the holes 604, 605 in the lateral surfaces of the powersupply modules 600. Further, since no vent holes are provided in therear of the power supply modules 600, the suction force provided by theleft-hand fan module 800 affects not only the air in the left-hand powersupply module 600 but also the air in the right-hand power supply module600. In this manner, the air in the right- and left-hand power supplymodules 600 and the controller modules 700 and 702 is entirely takeninto the left-hand fan module 800 and discharged outside. As a result,the interior of the chassis 100 can be cooled even when a fan module800, which plays an important role of cooling the interior of thechassis 100, becomes faulty. Therefore, the operation of the disk arraydevice can be continued. It should be noted that a failure in a fanmodule 800 is detected by controller module 700 or 702, and, forexample, the alarm buzzer 406 in the operation module 400 is caused tosound. In this way, the failure is reported to the maintenancepersonnel.

While the present invention has been described in terms of the presentembodiment, it should be understood that the invention is not limited tothe present embodiment, and that variations may be made withoutdeparture from the scope and spirit of the invention.

Advantages provided by the present embodiment will now be described.

The circuit board is capable of being attached in the chassis parallelto the opened front surface; the hard disk drive module is connected toa front side of the circuit board from the opened front surface of thechassis, the one side of the hard disk drive module being aligned withthe one side of the opened front surface of the chassis; the batterymodule is connected to the front side of the circuit board from theopened front surface of the chassis in a position adjacent the hard diskdrive module; and the controller module, the power supply module, andthe fan module are connected to a rear side of the circuit board fromthe opened rear surface of the chassis. Thanks to such a configuration,the hard disk drive module and the battery module can beinserted/removed into/from the front of the disk array device for moduleinsertion/removal purposes. Therefore, maintenance and inspection of thedisk array device can be made with ease. Further, by arranging the powersupply module, the controller module, and the fan module at the rear, itbecomes possible to prevent setting changes, such as cabling changes,from being made easily. These features increase the disk array device'sserviceability, maintainability, and security.

The circuit board has a front circuit board to which at least the harddisk drive module and the battery module are connected to the front sidethereof, and to which the power supply module and the fan module areconnected to the rear side thereof, and a rear circuit board to whichthe controller module is connected; and the front circuit board and therear circuit board are positioned adjacent and parallel to each otherand connected together with an electrical connector. Accordingly, sincethe circuit board size can be reduced, the circuit board can be mountedwithin a chassis for a small-size disk array device.

The controller module has a management portion for managing additionalinstallation of a disk array device. According to this configuration, itbecomes possible to decrease the number of modules and reduce the diskarray device size.

The controller module is substantially flat; a plurality of thecontroller modules are capable of being be arranged on the circuit boardadjacent to each other in a direction of the height of the chassis tomaximize the area in which the controller modules oppose each other; andthe connectors for connecting each of the controller modules to thecircuit board are arranged on the circuit board in the direction of theheight of the chassis. Accordingly, the length of the wiring on thecircuit board for connecting the controller modules can be minimized.This decreases the wiring space, thereby reducing the size of thecircuit board. Further, since crosstalk between wires can be avoided, itbecomes possible for the controller modules to share a cache.

The chassis has at least one hole and/or at least one protrusion; andthe circuit board has at least one protrusion that fits into the hole ofthe chassis and/or at least one hole into which the protrusion of thechassis fits. Thanks to such a feature, since the circuit board can bedirectly attached to the chassis with high accuracy, it possible toreduce the size of the chassis.

Further, at least one of the fan modules is arranged near each sidesurface of the chassis. By cooling the interior of the chassis with fansprovided near both side surfaces of the chassis, since it is unnecessaryto furnish the power supply module with a fan, downsizing of the diskarray device can be realized.

Each of the fan modules has a plurality of cooling fans; and air outletsof each of the cooling fans are oriented in directions different fromeach other to avoid interference between cooling air flow. Thanks tosuch a feature, since it is possible to discharge air from the coolingfans with high efficiency, it is possible to prevent the cooling airflow in the chassis from being disturbed.

The fan module is arranged near at least one side surface of thechassis; a partitioning plate is provided substantially in the middle ofboth side surfaces of the chassis; a set of the power supply modules isprovided, and at least one of the power supply modules is arranged oneach side of the partitioning plate; the controller module is arrangedacross the partitioning plate; and the partitioning plate is providedwith a vent hole. By adopting such a partitioning plate, it becomespossible to circulate cooling air within the chassis with only one fanmodule. Therefore, even if one of the fan modules becomes faulty, thewhole chassis can be continuously cooled. As a result, the availabilityof the disk array device can be enhanced.

The controller module is substantially flat; and the circuit board has aplurality of holes extending in a direction parallel to the controllermodule. Thanks to such a configuration, the cooling air flow within thechassis can be rectified when it passes through the circuit board. As aresult, the cooling air flow within the chassis is made to flow smoothlyto efficiently cool the interior of the chassis.

Further, the length of the one side of the opened front surface of thechassis is between 128 mm and 129 mm when the diameter of the disk is3.5 inches. Thanks to such a configuration, the height of the disk arraydevice can be set to no more than 3U (approximately 133.35 mm), which isdefined by the EIA Standard EIA-310-D.

Further, the operation module includes an alarm buzzer stop switch, anda power switch for the disk array device, the power switch having anON-side for turning the disk array device ON and an OFF-side for turningthe disk array device OFF; and the alarm buzzer stop switch is arrangedon the side of the ON-side of the power switch. Thanks to such aconfiguration, it becomes possible to prevent the disk array device frombeing turned OFF even if the power switch is inadvertently touched whenthe alarm buzzer stop switch is pressed to stop an alarm buzzer thatsounds in the event of an error.

Further, a setting switch is provided inside the operation module; andthe setting switch is capable of being manipulated for setup from aspace in front of a hard disk drive module adjacent the operationmodule. Such a structure enables setting of the disk array device whilekeeping the volume occupied by the operation module as small aspossible.

1-14. (canceled)
 15. A disk array device comprising: a plurality of harddisk drive modules each having a disk drive for recording data; acontroller module having a controller that controls writing/reading datainto/from the disk drives; a power supply module that supplies power tothe plurality of hard disk drive modules and the controller module; aplurality of fan modules having respective fans that cool the pluralityof hard disk drive modules, the controller module, and the power supplymodule; a chassis housing the plurality of hard disk drive modulesprovided on a front side thereof, and the controller module, the powersupply module, and the plurality of fan modules provided on a back sidethereof, the controller module and the power supply module being placedbetween the plurality of fan modules; and a circuit board, in thechassis, connected via connecters provided on a surface thereof on thefront side to the plurality of hard disk drive modules and connected viaconnecters provided on another surface thereof on the back side to thecontroller module, the power supply module, and the plurality of fanmodules; wherein the power supply module has first air holes used toallow air to flow in side directions toward the plurality of fanmodules.
 16. A disk array device according to claim 15, wherein the fanmodules are the same in shape, and of the fan modules, one fan module isplaced upside down with respect to an other fan module.
 17. A disk arraydevice according to claim 15, wherein each of the plurality of fanmodules has a plurality of fans therein, and wherein the plurality offans suck air from the controller module and the power supply modulethrough second air holes provided in the controller module and the powersupply module and discharge the air to outside through third air holesprovided in the back of the plurality of fan modules.
 18. A disk arraydevice according to claim 15, wherein each of the plurality of fanmodules has a plurality of fans therein, and the plurality of fans suckair from the power supply module through the first air holes, anddischarge the air to outside through third air holes provided in theback of the plurality of fan modules, and wherein an outlet of a firstone of the plurality of fans is placed such that the outlet of the firstone is different, in distance from an inner side surface of the chassis,from an outlet of a second fan of the plurality of fans.
 19. A diskarray device according to claim 15, wherein the opposite side of thecontroller module and the power supply module from the circuit board isclosed by a wall without an air hole for the cooling air.
 20. A diskarray device according to claim 15, wherein a plurality of thecontroller modules are provided, and second air holes are providedbetween each of the fan modules and the power supply module adjacent tothe each fan module, the second air holes being used to allow coolingair to flow in directions toward the fan modules.
 21. A disk arraydevice according to claim 15, second air holes are provided between oneof the fan modules and the controller module, the second air holes beingused to allow cooling air to flow in directions toward the fan modules.22. A disk array device according to claim 15, wherein formed in thecircuit board are fourth air holes used to allow cooling air which hasbeen used to cool the plurality of hard disk drive modules to flow intothe controller module and the power supply module.
 23. A disk arraydevice according to claim 15, wherein the power supply module has no fantherein, and cooling air flowing into the power supply module isdischarged by sucking by the fan modules from the power supply modulethrough the first air holes of the power supply module.
 24. A disk arraydevice according to claim 15, wherein a plurality of the controllermodules are provided, and each of the plurality of controller modulescomprises an enclosure which, when connected to an other disk arraydevice having a plurality of hard disk drive modules, manages the otherdisk array device.
 25. A disk array device according to claim 15,wherein each of the plurality of fan modules has a plurality of fanstherein, and the plurality of fans suck cooling air from the powersupply module through the first air holes, and discharge the cooling airto outside through third air holes provided on the opposite side of theplurality of fan modules from the circuit board, and wherein an outletof a first one of the plurality of fans is placed so as to avoid asecond fan of the plurality of fans blocking a path for air dischargedthrough the outlet.
 26. A disk array device according to claim 15,wherein each of the plurality of fan modules has a plurality of fanstherein, and the plurality of fans suck cooling air from the powersupply module through the first air holes, and discharge the cooling airto outside through third air holes provided on the opposite side of theplurality of fan modules from the circuit board, and wherein an outletof a first one of the plurality of fans is placed such that a path forair discharged through the outlet is different from a path for airdischarged through an outlet of a second fan of the plurality of fans.27. A disk array device according to claim 15, wherein a height of thechassis is equal to or less than 3U defined by an EIA STANDARDEIA-310-D.
 28. A disk array device according to claim 15, wherein theplurality of hard disk drive modules comprise 14 hard disk drive modulesprovided on a side of the chassis on which one surface of the circuitboard exists.
 29. A disk array device comprising: a plurality of harddisk drive modules each having a disk drive for recording data; acontroller module having a controller that controls writing/reading datainto/from the disk drives; a power supply module that supplies power tothe plurality of hard disk drive modules and the controller module; aplurality of fan modules having respective fans that cool the pluralityof hard disk drive modules, the controller module, and the power supplymodule; a chassis housing the plurality of hard disk drive modulesprovided on a front side thereof, and the controller module, the powersupply module, and the plurality of fan modules provided on a back sidethereof, the controller module and the power supply module being placedbetween the plurality of fan modules; and a circuit board, in thechassis, connected via connecters provided on a surface thereof on thefront side to the plurality of hard disk drive modules and connected viaconnecters provided on another surface thereof on the back side to thecontroller module, the power supply module, and the plurality of fanmodules; wherein the fan modules are the same in shape, and of the fanmodules, one fan module is placed upside down with respect to an otherfan module.
 30. A disk array device according to claim 29, wherein thepower supply module has first air holes used to allow air to flow inside directions toward the plurality of fan modules.
 31. A disk arraydevice according to claim 30, wherein each of the plurality of fanmodules has a plurality of fans therein, and the plurality of fans suckair from the power supply module through the first air holes, anddischarge the air to outside through third air holes provided in theback of the plurality of fan modules, and wherein an outlet of a firstone of the plurality of fans is placed such that the outlet of the firstone is different, in distance from an inner side surface of the chassis,from an outlet of a second fan of the plurality of fans.
 32. A diskarray device according to claim 30, wherein the power supply module hasno fan therein, and cooling air flowing into the power supply module isdischarged by sucking by the fan modules from the power supply modulethrough the first air holes of the power supply module.
 33. A disk arraydevice according to claim 30, wherein each of the plurality of fanmodules has a plurality of fans therein, and the plurality of fans suckcooling air from the power supply module through the first air holes,and discharge the cooling air to outside through third air holesprovided on the opposite side of the plurality of fan modules from thecircuit board, and wherein an outlet of a first one of the plurality offans is placed so as to avoid a second fan of the plurality of fansblocking a path for air discharged through the outlet.
 34. A disk arraydevice according to claim 29, wherein each of the plurality of fanmodules has a plurality of fans therein, and wherein the plurality offans suck air from the controller module and the power supply modulethrough second air holes provided in the controller module and the powersupply module and discharge the air to outside through third air holesprovided in the back of the plurality of fan modules.
 35. A disk arraydevice according to claim 29, wherein the opposite side of thecontroller module and the power supply module from the circuit board isclosed by a wall without an air hole for the cooling air.
 36. A diskarray device according to claim 29, wherein a plurality of thecontroller modules are provided, and second air holes are providedbetween each of the fan modules and the power supply module adjacent tothe each fan module, the second air holes being used to allow coolingair to flow in directions toward the fan modules.
 37. A disk arraydevice according to claim 29, second air holes are provided between oneof the fan modules and the controller module, the second air holes beingused to allow cooling air to flow in directions toward the fan modules.38. A disk array device according to claim 29, wherein formed in thecircuit board are fourth air holes used to allow cooling air which hasbeen used to cool the plurality of hard disk drive modules to flow intothe controller module and the power supply module.
 39. A disk arraydevice according to claim 29, wherein a plurality of the controllermodules are provided, and each of the plurality of controller modulescomprises an enclosure which, when connected to an other disk arraydevice having a plurality of hard disk drive modules, manages the otherdisk array device.
 40. A disk array device according to claim 30,wherein each of the plurality of fan modules has a plurality of fanstherein, and the plurality of fans suck cooling air from the powersupply module through the first air holes, and discharge the cooling airto outside through third air holes provided on the opposite side of theplurality of fan modules from the circuit board, and wherein an outletof a first one of the plurality of fans is placed such that a path forair discharged through the outlet is different from a path for airdischarged through an outlet of a second fan of the plurality of fans.41. A disk array device according to claim 29, wherein a height of thechassis is equal to or less than 3U defined by an EIA STANDARDEIA-310-D.
 42. A disk array device according to claim 29, wherein theplurality of hard disk drive modules comprise 14 hard disk drive modulesprovided on a side of the chassis on which one surface of the circuitboard exists.